GPM not reachable

I just installed Grav with Composer on my Mac as per: https://learn.getgrav.org/basics/installation
I now want to install the admin plugin so I type:

$ bin/gpm install admin

This returns:

GPM Releases Configuration: Stable

[RuntimeException]                                                                            
GPM not reachable. Please check your internet connection or check the Grav site is reachable

My internet connection is fine and the Grav site appears reachable so not sure what to do.

I have followed the instructions at https://learn.getgrav.org/troubleshooting/common-problems#cannot-connect-to-the-gpm but with no luck

I didn't do the bit that references:

system.gpm.verify_peer

Because I don't know what that means.

Any help is appreciated.

I think I have done it!
I edited site/user/config/system.yaml "verify_peer: false" and now I have been able to install the admin plugin.
Not sure why it wouldn't work normally though.

It's a proxy issue, usually. I've seen at least a couple Github issues mention this. I think the team is looking into a fix.

Alternatively try turning of the Peer Verify option in the system config.